Depends on what defines “orgy” in your mind? Are you seeking a bordello which organises such with w/l providing this as a service?
A number of places where group sex occurs regularly exist in Perth. Group sessions can include MMF (or more
), FFM, partner swapping etc.
Opportunities can include either organised gangbangs or spontaneous group sessions when attending a suitable venue where chemistry takes over.
There are several “swingers” venues at commercial premises in Perth (several threads discuss these - search swingers) and events most day -both daytime or evenings, as well as numerous, but more “exclusive” invite only, private parties if you are known as a regular in the swinging ”scene” - generally on weekends.